|Publication number||US7909263 B2|
|Application number||US 10/886,757|
|Publication date||Mar 22, 2011|
|Filing date||Jul 8, 2004|
|Priority date||Jul 8, 2004|
|Also published as||US20060006250, WO2006017002A2, WO2006017002A3|
|Publication number||10886757, 886757, US 7909263 B2, US 7909263B2, US-B2-7909263, US7909263 B2, US7909263B2|
|Inventors||Daniel S. Marshall|
|Original Assignee||Cube Technology, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (37), Referenced by (2), Classifications (21), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This invention relates to particle dispersion.
More particularly, the present invention relates to particle dispersion in a spray application.
Dispersion of fine particles for various applications, such as plasma spray deposition, combustion, and the like, has been successfully accomplished for particles of relatively large size. Once a minimum particle size is reached, such as less than ten microns, particle attraction forces overcome gravitational forces resulting in clumping and cohesion of the particles. When this occurs, dispersion of these very fine particles is difficult to achieve.
A specific area of interest is the use of particles in plasma sprays. Currently, plasma sprays are employed for material deposition, formation and alloying. RF plasma spray devices inject powders formed of fine particles into plasma created by RF induction coils. The particles in the powder can be softened or even completely melted. The particles are then deposited from the plasma onto a substrate or cooled, allowing surface tension to create spheres of the material which are then collected. While very useful for relatively large particles, such as particles greater than 10 microns, smaller Nano sized particles do not work well in RF plasma spray devices. Specifically, as the particle size decreases, such as less than ten microns, inter-particle forces are equal or greater than gravity, resulting in clumping of the powders. Recently, plasma devices have been made which permit very fine particles to be efficiently injected into plasma for deposition. These devices are employed in what is called suspension plasma spray.
Suspension plasma spray devices utilize particles suspended in a liquid carrier. The suspension is brought into the plasma discharge as a stream of fine droplets by an atomizing probe. Very fine particles are easily handled with the suspension. When the suspension is introduced into the plasma discharge, the carrier substance is vaporized with the particles agglomerating into partially or totally melted drops. These drops are then deposited or collected as desired. While effective, the droplets contain multiple particles which agglomerate with vaporization of the carrier. Thus, the resulting agglomerated material includes multiple particles, the agglomeration having a much greater size than the individual particles. Additionally, this method is used as a means of alloying materials. When particles of different materials are employed, the partial or complete melting of the agglomerated materials results in partially or completely alloyed material.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object the present invention to provide a new and improved method of dispersing fine particles in a spray.
Another object of the present invention is to provide a method of dispersing very fine particles in a gaseous spray.
Yet another object of the present invention is to provide a method of simultaneously depositing very fine particles of different materials.
Briefly, to achieve the desired objects of the present invention in accordance with a preferred embodiment thereof, provided is a method of dispersing particles in a spray. The method includes providing a liquid carrier having a critical point and particles of a material. The particles are dispersed in the liquid carrier. A supercritical carrier containing dispersed particles is created by driving the liquid carrier containing dispersed particles above the critical point. The supercritical carrier containing dispersed particles is then discharged.
In a specific aspect of the present invention, discharging the supercritical carrier includes decreasing the pressure of the supercritical carrier containing dispersed particles to form a vapor carrier containing dispersed particles. Additionally, the temperature of the supercritical carrier can be decreased if desired, to form a proportion of liquid carrier with the vapor carrier containing dispersed particles therein. It is desirable that the proportion of liquid carrier to vapor carrier not exceed 1:1.
In another aspect of the present invention, a method of plasma spraying fine particles is provided. In this method, a plasma discharge is provided. A supercritical carrier containing dispersed particles is injected into the plasma discharge. In a particular aspect, the supercritical carrier containing particles includes particles of at least two different materials. Also, injecting the supercritical suspension of particles includes mixing particles with a liquid carrier and applying heat and pressure to at least a critical point of the liquid carrier. The step of injecting can further include decreasing the pressure of the supercritical carrier containing dispersed particles, thereby forming a vapor carrier containing dispersed particles therein.
The foregoing and further and more specific objects and advantages of the invention will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment thereof, taken in conjunction with the drawings in which:
A dispersion of fine particles in a spray has many potential applications. These applications include deposition of materials, combustion processes for energy conversion and the like. In this description, fine particles refer to particles of material which have reached a minimum size in which particle attractive forces are stronger than the force of gravity or other forces which tend to separate particles. In other words, the particles are of such a small size as to tend to clump, cake or otherwise adhere to one another. This is typically seen in particles less than 5 microns in size.
As an example of the inability to properly disperse particles, gasses have much fewer molecules in a volume than do liquids. The relatively widely spaced molecules are insufficient to separate very small particles and prevent cohesion there between. Therefore, the particles are inadequately dispersed (form clumps) in a vapor carrier. Liquids have a much denser concentration of molecules and therefore liquid carriers more efficiently separate particles, dispersing them throughout and preventing clumping due to the relatively large number of particles separating each particle. Unfortunately, for the present purposes, liquids also have surface tension which results in droplets containing multiple particles when sprayed. Evaporation of the liquid carrier will result in agglomerations of particles. Thus, each carrier substance, vapor and liquid, has its limitations, preventing fine particles being properly dispersed in a spray.
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Thus, supercritical carrier 30 is adjusted with a temperature and pressure appropriate to cross line 16 from supercritical zone 20 into vapor zone 12. Variations in the proportion of vapor carrier and liquid carrier can be achieved as desired, with adjustments to the position of the supercritical carrier within supercritical zone 20. As the vapor carrier carrying the particles is injected into plasma discharge 32 through nozzle 34, the vapor carrier evaporates leaving a dispersion of fine particles within plasma discharge 32. Since a vapor carrier and not a liquid carrier is employed, droplets are avoided reducing or eliminating agglomeration of the particles. When the vapor evaporates, the fine particles are dispersed throughout plasma discharge 32, preventing clumping or agglomeration. In this manner, particles of different materials will not form alloys within the plasma. Instead, each individual particle will soften or liquify as desired and can be used in a selected application. A specific application, by way of example, is the deposition of particles of different material on a substrate to form of a mosaic structure. Formation of the structure has been disclosed in pending U.S. patent application Ser. No. 10/836,465, entitled THERMOELECTRIC MATERIAL STRUCTURE AND METHOD OF FABRICATION, filed 30 Apr. 2004, herein incorporated by reference.
While fine particles of many different materials may be employed, the particles are generally selected from groups consisting of insulators, semi-conductors, conductors, and hopping conductors. Additionally, while an RF plasma spray is employed in the preferred embodiment, it will be understood that other plasma devices can be employed. Also, plasma is intended to include flame spray applications.
Various changes and modifications to the embodiments herein chosen for purposes of illustration will readily occur to those skilled in the art. To the extent that such modifications and variations do not depart from the spirit of the invention, they are intended to be included within the scope thereof, which is assessed only by a fair interpretation of the following claims.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4582731||Sep 1, 1983||Apr 15, 1986||Battelle Memorial Institute||Supercritical fluid molecular spray film deposition and powder formation|
|US4734451||Mar 12, 1986||Mar 29, 1988||Battelle Memorial Institute||Supercritical fluid molecular spray thin films and fine powders|
|US4923720||Oct 4, 1989||May 8, 1990||Union Carbide Chemicals And Plastics Company Inc.||Supercritical fluids as diluents in liquid spray application of coatings|
|US4970093 *||Apr 12, 1990||Nov 13, 1990||University Of Colorado Foundation||Chemical deposition methods using supercritical fluid solutions|
|US5302414 *||May 19, 1990||Apr 12, 1994||Anatoly Nikiforovich Papyrin||Gas-dynamic spraying method for applying a coating|
|US5548004 *||Jan 11, 1995||Aug 20, 1996||Ferro Corporation||Method of preparing coating materials|
|US5639441 *||Apr 8, 1994||Jun 17, 1997||Board Of Regents Of University Of Colorado||Methods for fine particle formation|
|US5652021||Apr 3, 1995||Jul 29, 1997||Georgia Tech Research Corp.||Combustion chemical vapor deposition of films and coatings|
|US5708039||Jun 14, 1996||Jan 13, 1998||Morton International, Inc.||Smooth thin film powder coatings|
|US5744777||May 31, 1996||Apr 28, 1998||Northwestern University||Small particle plasma spray apparatus, method and coated article|
|US5789027 *||Nov 12, 1996||Aug 4, 1998||University Of Massachusetts||Method of chemically depositing material onto a substrate|
|US5997956||Aug 2, 1996||Dec 7, 1999||Microcoating Technologies||Chemical vapor deposition and powder formation using thermal spray with near supercritical and supercritical fluid solutions|
|US6095134||Apr 24, 1997||Aug 1, 2000||The Board Of Regents Of The University Of Co||Methods and apparatus for fine particle formation|
|US6114414 *||Jun 25, 1997||Sep 5, 2000||Morton International, Inc.||Continuous processing of powder coating compositions|
|US6240859||May 5, 2000||Jun 5, 2001||Four Corners Group, Inc.||Cement, reduced-carbon ash and controlled mineral formation using sub- and supercritical high-velocity free-jet expansion into fuel-fired combustor fireballs|
|US6368665||Apr 29, 1998||Apr 9, 2002||Microcoating Technologies, Inc.||Apparatus and process for controlled atmosphere chemical vapor deposition|
|US6433933||Mar 29, 2001||Aug 13, 2002||Palm, Inc.||Internal diffuser for a charge controlled mirror screen display|
|US6500350||Feb 8, 2001||Dec 31, 2002||Morton International, Inc.||Formation of thin film resistors|
|US6502767 *||May 2, 2001||Jan 7, 2003||Asb Industries||Advanced cold spray system|
|US6589312||Mar 13, 2000||Jul 8, 2003||David G. Snow||Nanoparticles for hydrogen storage, transportation, and distribution|
|US6660176||Jan 24, 2002||Dec 9, 2003||Virginia Commonwealth University||Molecular imprinting of small particles, and production of small particles from solid state reactants|
|US6716891||May 26, 2000||Apr 6, 2004||Basf Coatings Ag||Coating material that can be cured thermally or by actinic radiation, and its use|
|US6727316||Jun 23, 2000||Apr 27, 2004||Basf Coatings Ag||Coating material and its use for producing filler coats and stone impact protection primers|
|US6728092||Mar 30, 2001||Apr 27, 2004||Shipley-Company, L.L.C.||Formation of thin film capacitors|
|US6734379||Sep 6, 2002||May 11, 2004||Olympia Group, Inc.||Electronic power tool lock-out mechanism|
|US6736996||Jul 20, 2000||May 18, 2004||North Carolina State University||Compositions for protecting civil infrastructure|
|US6737468||Jun 30, 2000||May 18, 2004||Basf Coatings Ag||Base coat and its use for producing color and/or effect-producing base coatings and multi-layer coatings|
|US6749902 *||May 28, 2002||Jun 15, 2004||Battelle Memorial Institute||Methods for producing films using supercritical fluid|
|US6821429 *||Dec 15, 2000||Nov 23, 2004||Separex||Method and device for capturing fine particles by trapping in a solid mixture of carbon dioxide snow type|
|US20010039919||Jul 3, 2001||Nov 15, 2001||Hunt Andrew T.||Chemical vapor deposition and powder formation using thermal spray|
|US20020015797||Aug 3, 2001||Feb 7, 2002||Hunt Andrew T.||Chemical vapor deposition and powder formation using thermal spray with near supercritical and supercritical fluid solutions|
|US20030047617||Jun 27, 2001||Mar 13, 2003||Subramaniam Shanmugham||Method of pepositing materials|
|US20030222017||May 28, 2002||Dec 4, 2003||Battelle Memorial Institute||Electrostatic deposition of particles generated from rapid expansion of supercritical fluid solutions|
|US20030222018||May 28, 2002||Dec 4, 2003||Battelle Memorial Institute||Methods for producing films using supercritical fluid|
|US20030222019||May 28, 2002||Dec 4, 2003||Battelle Memorial Institute||Electrostatic deposition of particles generated from rapid expansion of supercritical fluid solutions|
|US20040011245||Aug 20, 2001||Jan 22, 2004||Sankar Sambasivan||High temperature amorphous composition based on aluminum phosphate|
|US20040043140||Nov 20, 2002||Mar 4, 2004||Ramesh Jagannathan||Solid state lighting using compressed fluid coatings|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US8030194 *||Sep 22, 2005||Oct 4, 2011||Technion Research And Development Foundation Ltd.||Spray method for producing semiconductor nano-particles|
|US20090263956 *||Sep 22, 2005||Oct 22, 2009||Technion Research And Development Foundation Ltd.||Spray method for producing semiconductor nano-particles|
|U.S. Classification||239/10, 239/419, 239/310, 427/569, 239/135, 427/377, 239/13, 239/128|
|Cooperative Classification||B05D2401/90, B05D1/62, B05D1/025, B05B9/005, B05B7/22, B05D1/12, C23C4/134|
|European Classification||B05D1/12, B05D1/02C, C23C4/12L, B05D1/62, B05B9/00C|
|Sep 7, 2004||AS||Assignment|
Owner name: CUBE TECHNOLOGY INC., ARIZONA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MARSHALL, DANIEL S.;REEL/FRAME:015758/0807
Effective date: 20040728
|Oct 31, 2014||REMI||Maintenance fee reminder mailed|
|Mar 22, 2015||LAPS||Lapse for failure to pay maintenance fees|
|May 12, 2015||FP||Expired due to failure to pay maintenance fee|
Effective date: 20150322